Thumbsucking or the insertion of other habit instruments (e.g., other fingers) within the mouth typically causes an "overjet" condition, wherein the lower central incisors are moved both labially (out) and gingivally (down), and the upper central incisors are moved both gingivally (up) and labially (out), thus typically developing a gap between the lower and upper incisors when the mouth is closed. Although there are orthodontic treatments available for correcting overjet, the continuation of the habit during the treatment process further complicates the treatment and typically prevents successful correction of the overjet condition.
One method for correcting thumbsucking (or the insertion of other habit instruments) is to place a cage or guard device on the thumb (or other habit instrument), or to apply a foul or sharp tasting substance to the thumb or to the guard device attached to the thumb. These methods interfere with the normal use of the patient's hands, however, and thus typically do not achieve sufficient patient compliance.
Another habit correction method is to place a bar or guard device within the oral cavity of the mouth on the lingual side of the dentition to deter the insertion of the thumb (or other habit instrument) within the mouth. One such device is custom fabricated for each patient and is permanently attached on its distal ends, e.g., by soldering, to a pair of molar bands attached to the patient's upper molars. A base defines a surface which conforms to the morphology of the palate of the mouth and a guard projects downwardly from the base on the lingual side of the upper incisors. The guard is located lingually with respect to the upper incisors and typically includes several pointed surfaces to deter insertion of the thumb (or other habit instrument).
Because the guard is located lingually with respect to the dentition, the morphology of the mouth prevents the guard from having sufficient height to prevent insertion of the thumb (or other habit instrument) into the mouth. Thus, although the device hinders continuation of the habit, the device can be bypassed. The pointed surfaces on the guard can also cut the thumb tissue of particularly persistent patients. Because this device is permanently attached to molar bands (usually by soldering), once the device is no longer needed, the molar bands must be removed to discard the device, which can be a relatively time consuming procedure. This, coupled with the custom fabrication, makes the device relatively expensive.